The present invention relates in general to instrument systems for data acquisition, processing and evaluation for determining the neuro-psycho-physical state of a person. In particular, the present invention relates to a portable system for automatically determining the neuro-psycho-physical condition of patients affected by Paralysis Agitans (Parkinson""s disease) and other similar type diseases.
Parkinson""s disease is a degenerative process of the central nervous system having a slow and progressive evolution. The anatomopological alteration includes damage of neurons having dopaminergical melaninic content, which is located in the cerebral trunk, with consequent reactive gliosys. Biochemical studies have demonstrated a dysfunction of the dopaminergical nigrostriatal system. Dopamine is a chemical medium by which neurons communicate among each other. Parkinson""s disease exhibits rigidity (muscular hypertonicity), akinesys, and tremor.
Rigidity opposes passive stretching of the muscles with a constant resistance that yields movement. There is a prevalence of the hypertonicity of the flexor muscles and this explains the general posture of the patient: head and trunk forward leaning, arms slightly flexed, and at the hand level the thumb is flexed.
Acinesy is characterized by slowness and global reduction of voluntary mobility. The patient is inexpressive. There is a reduction of the pendular movements of the arms during walking and a person with Parkinson""s disease has difficulties in executing alternate movements rapidly, like drumming with fingers, making moving shadows, and making flex-extensions of the first finger. In addition, handwriting tends to become small (micrography), speech tends to become monotonic with sudden accelerations.
Acinesy may have a unilateral beginning and predominance. Sometimes following an emotion, acinesy may suddenly disappear. This demonstrates that the neural structures for the movements are not inhibited, but their stimulation requires exceptional excitations.
Tremor is present at rest. It generally disappears when executing a voluntary movement, during sleep, and following a complete muscle relaxation. Emotions, stress, and concentration efforts stimulate tremor. Moreover, tremor of an upper limb may appear while exerting the other upper limb. Generally, it is a regular tremor with a rhythm of 4-8 cycles per second. It starts at the extremity of the upper limb with alternate movements of flexal-extension of the fingers and of the thumb (similar to the gesture of counting coins). Other symptoms are hypersalivation, hypersweating, and orthostatic hypotension while osteotendineous reflexes are normal.
In view of the evolutive character of the disease, methods for multiparametric assessment have been developed to provide an incruent instrumental indication of the neuro-psycho-physical state of a patient.
Multiparametric measurement of reaction times of an individual may be useful for establishing the state of neuro-psycho-physical health of a generally healthy person. This is in addition to aiding diagnosis and monitoring of the progress of Parkinson""s disease. Multiparametric measurement is an excellent way of discriminating alterations of reactive parameters due to other causes than the disease itself, such as the ingestion/consumption of alcoholics, drugs, psycho-pharmaceutical products or other substances that have an effect on the reactive and coordination capacities of a person.
A known method of diagnostic testing is the multiparametric measurement of the times of vocal reaction, which is described in the book xe2x80x9cNeurologie del comportamento (errori e correzione del controllo cerebrate)xe2x80x9d by P. Pinelli, Ed. Ambrosiana, 1997.
The person is instructed to provide a certain reply to a given signal. The reply may include pressing a push button as fast as possible. Stimulations of various types occur from time to time, and the person must press on a keyboard a certain key associated to the particular stimulation. To restrict the period of attention of the person, an alerting signal may precede the stimulation assignment.
The stimulation may be visual or audio. It may be a displayed test, an acronym, a word, or a phrase. The stimulations are presented in casual succession and the person may be called to pronounce the displayed expressions loudly to implement what is referred to as a reading reaction. Other stimulations may be figures, of which the person must pronounce the name, implementing what is normally called a reaction to figure identification.
In all these cases, every sound expressed is recorded as such through a microphone. In all the reactions, the time between the display of the stimulation to the instant when the answer begins is defined as the time of reaction. Since individual reaction time is normally slightly different from the preceding one and from the successive one in a series of reactions tests, the average and the relative standard deviation for a certain number of reaction tests to the same type of stimulation are calculated and recorded.
Typically, to obtain a significant average value about 10-12 reactions tests may be necessary. The brain functions statically and such a mode of functioning implies oscillations of the times and characters of performances. It is therefore important to detect also the duration of the reply beside its correctness, both in relationship to the stimulation as well as a sequence of movements. Accuracy of the reply is also important and in case of verbal replies, even sound frequencies may be analyzed.
The utility of measuring also the duration of the reply depends from the fact that it reflects the sequence of the various movements that are notably commanded through very complex neural controls. Another method of test is described in the article: xe2x80x9cAdvances In Occupational Medicine And Rehabilitationxe2x80x9d by F. Ceriani et al.
This method rests on two tests. One of immediate reading and one of retarded reading. In the immediate reading, the patient is requested to pronounce the word immediately as displayed on the screen. In the retarded reading test, the patient must wait for an execution command given by a series of asterisks that appear above and below the displayed word. In a first test the reaction time is measured. In a second test the time for executing the central cerebral processing is assessed, and only after the time taken by the articulation. The patient is requested to translate a conceptual structure in a linguistic structure highlighting all the aspects, such as the grammatical coding of a message, the coding of a phonetic diagram and of a diagram of the articulation of each word.
In the last phase a phonetic diagram based on the muscle reaction, on the larynx and supra-larynx respiration, and on the oromandibular system is effected. In this way the synchronization between articulation and time necessary to express the words may be verified.
A different approach of instrumental testing includes a bioengineering system of acquisition and production of data on the movement of a finger. This system was developed by Professor Alberto Rovetta, and is based on the following protocols: fast movement, uncontrolled movement, controlled movement, and movement with virtual control.
Referring to fast movement, the person must touch from an initial reference point with the first finger of the hand a target as fast as possible. This is designed to measure the impressed force while in parallel other parameters are detected, among which include the angular position and the velocity of the finger and the reaction time.
Referring to uncontrolled movement, the person must make the same movement of the preceding protocol without watching their own finger. Instead, the person must do it by memorizing the procedure learned during the execution of the preceding protocol of fast movement, thus activating the person""s working memory. For a controlled movement, the person must control the speed of execution in such a way that by observing the target, he may have to slow down his movement before hitting it.
Referring to movement with virtual control, the person is to follow on a graphic display the virtual image of his finger and at the moment in which his finger touches the real target, the virtual finger on the display changes color. This indicates the reaching of the target and the end of the test.
The bioengineering system is formed by the following. An exoskeleton mounted on a stand for establishing the position of the finger to be placed inside a glove like receptacle; potentiometers in correspondence to the joints flanges of the finger for detecting their movements; surface electrodes which through a bichannel probe provide a signal to an electromyograph; and instrumentation for measuring the force exerted on a target lamina on which strain gages are mounted.
The exoskeleton is supported by a common desktop PC with a ISA/EISA data acquisition card (model PC LPM 16 National Instruments) and by a software developed in Microsoft Visual C++ with development environment libraries LabWindows 2.2.1 of National Instruments, for data acquisition, analysis and formation of a graphic interface. A general scheme of the system is depicted in FIG. 1, and FIGS. 2 and 3 are photographs of the exoskeleton. A portable version of the above system employing a portable laptop computer using a data acquisition card PC MCIA II (Model DAQ Card-700 of National Instruments) is depicted in FIGS. 4 and 5.
Though implementable in a transportable form, these instrumental monitoring systems of the neuro-psycho-physical condition remain extremely burdensome and require a time consuming preparation, including disposing and connecting the various components. It is a recurrently observed characteristic of reactive capabilities of an individual with a remarkably high degree of subordination to the emotional state of the person.
Referring to the case of a trivial blood pressure test, submission to a test of a neuro-psycho-physical condition may induce in a person an emotional state that markedly influences the results of the testing. Such an influence could be greatly reduced when not completely eliminated if the test could be completely and easily self-managed by the patient without requiring any preparatory work. Moreover, a frequent execution of the test, for example daily, would make it soon emotionally insignificant, thus enhancing the generation of more reliable data.
It is evident the interest and utility of a diagnostic method of the neuro-psycho-physical state of a person based on instrumentally generated data, implementable with a portable battery powered stand-alone instrument that does not require trimming or set-up operations and can be used at any moment of the day and practically in any place.
In view of the foregoing background, an object of the present invention is to fulfill the above described fundamental requirements.
It has been found that a multiparametric analysis of reaction times and of ergometric data in executing simple actions such as the pressing of a push button is greatly simplified and rendered far more reliable in terms of the results of the assessment by calculating the power that is exerted in executing the action of pressing a push button, as contemplated by the test.
Measurement of the power, intended in the present context, as the product of a force by a mean velocity or the product of the force by the distance covered by the moving finger within a certain time, has been demonstrated to be strictly correlated to the command process of the brain and of the nervous system.
In case of execution of an action of relatively small duration, such as the pressing of a push button, an instantaneous measurement of the power exerted may be obtained by instrumental measurements. Such a measure provides a good assessment of the way the brain command propagates through the neural and sensor circuits that control the execution of the required action. This implies a negligible physical effort, such as pressing a push button in a controlled manner.
In systems requiring actions to be developed in a relatively long span of time, the brain command does not appear to be determined instant by instant during the entire execution, but only in starting the action. Thereafter, the brain command is performed under a complex feedback control of the movement. In contrast, execution of an action of relatively brief duration, such as the pressing of a push button through a travel distance of few millimeters (to a mechanical stop), the ergometric data of the action and, in particular, the power exerted in substantial absence of feedback control, proves itself strongly tied to the brain command (i.e., reactivity).
Analysis of the data of these tests by a fuzzy logic microprocessor on the basis of a specific software is extremely simplified by a predetermination of the value of the exerted power in performing the action. The determination may be made by a simple logic circuitry. The calculated power value synthesizes optimally information on the speed of execution of the action and on the force exerted in performing it.
Moreover, by employing fuzzy logic processing there is no need to preestablish thresholds set by the doctor. This allows less rigid consequences in the overall result of the assessment. The whole monitoring system of the neuro-psycho-physical condition of a person may be contained in a device that can be easily handled with both hands or even with a single hand. The device may have a size and shape similar to those of a common remote control, cellular telephone or of a joystick.
Such a miniaturization of a battery powered system is extremely practical. Immediate use by the patient implies eventually a substantial disappearance of perturbed emotional states of the patient in performing the test after an initial period of daily use of the instrument.
The system according to the present invention for instrumentally monitoring of the neuro-psycho-physical condition of a person comprises a push button equipped with means for detecting the initial (start) instant of the pressing, and of the stopping instant when the push button is pushed against a mechanical stop equipped with a dynamometer or a strain gage providing a force signal. The system also includes an amplifier for the force signal of the dynamometer or strain gage, a pass band filter, and an analog/digital converter outputting a digital signal representative of the force exerted on the push button.
The system further includes a logic control and processing circuit of the start and stop signals and of the force signal for calculating on the basis of the length of the travel of the push button (which normally is a few millimeters) a digital value representative of the power exerted by the finger in pressing the push button. A fuzzy logic microprocessor performs a multiparametric evaluation of the time and ergometric values producing an index representative of the neuro-psycho-physical condition. A memory stores the processed data and/or the produced indexes, and includes interface circuits with the logic circuit and/or with the microprocessor. A display unit, an audio command generating unit, a keyboard or equivalent interface for start-up and selection of the type of test, and a battery is also included.
The system of the invention is entirely contained in an ergonomically shaped casing that may be handled using a single hand or with both hands. The casing may have the shape of a remote control or of a portable telephone or of a joystick, the latter being particularly suited to be handled with a single hand. A finger of which is used for exerting the pressing action of the push button.
In case the instrument of the invention is used for clinical purposes, such as monitoring the progress of the disease in a person having the Parkinson""s disease, for example, the memory may record in a nonvolatile manner the data detected and elaborated during a certain number of tests. The memory may record repeatedly at regular (e.g., daily) intervals in a format not readable by the patient. The system may be connected to the data base of a medical center for downloading the acquired data in an appropriate coded format.
The visual interface of the instrument may be a liquid crystal display or any other alphanumeric and/or graphic display. The visual interface provides an interface of communication with the person during the test. The person is able to choose the specific test to be performed, and the visual interface illustrates this to the patient and, eventually for communicating the results of the tests in a quantitative or qualitative way, even by way of a number of predefined messages. Both the analysis software of the data as well as the communication messages with the patient or the person that undertakes and/or supervises the test, may be recorded in a nonvolatile manner, eventually modifiable by reprogramming the system""s memory.
The acoustic interface may provide by itself or in cooperation with the display unit to the person doing the test preestablished alerting and start commands for executing the required actions. Optionally, the system may include a sensor for movement, such as an accelerometer, for example, for assessing the eventual presence when the hand tremors while holding the instrument, or of the person subjecting himself to the test and the frequency of the eventually present tremor.
Alternatively, instead of an accelerometer, the system may optionally include a subsystem of classification of movement employing an ON/OFF sensor. The sensor detects the tremor of the hand outputting an analog signal that is converted in a digital signal and is then stored. The conversion may be such that the bits 1 and 0 correspond to a closed and open condition of electrical contacts. Parameters representing the duration of the accelerations in the same direction and the number of transitions within a preestablished period of time may be fed to the fuzzy logic processing system.
Optionally, the system of the invention may also include a block of classification of the vocal articulation generating further parameters to be fed to the fuzzy logic processing system.